An issue with libX11?

An issue with libX11?

[Angelo Graziosi]

 From another application I have an issue with libX11 which I can 
reproduce with the following STC,


$ cat getch_test.c
/*
   gcc getch_test.c -lX11 -o getch_test.out

   DISPLAY=127.0.0.1:0.0 ./getch_test.out
*/

#include <stdio.h>
#include <stdlib.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/Xos.h>
#include <X11/Xatom.h>
#include <X11/keysym.h>

Display *dis;
Window win;

int fun()
{
   XEvent event;
   char c;

   printf("1\n");

   while(1)
   {
     printf("2\n");
     XNextEvent(dis, &event);

     printf("3\n");

     if (event.type == KeyPress)
     {
       c = (char) XLookupKeysym(&event.xkey, 0);
       return (int) c;
     }
   }
}

int main()
{
   dis = XOpenDisplay(NULL);
   win = XCreateSimpleWindow(dis, RootWindow(dis, 0), 1, 1, 500, 500,
                             0, BlackPixel (dis, 0), BlackPixel(dis, 0));

   XMapWindow(dis, win);
   XFlush(dis);

   printf("Press a key:\n");
   fun();

   /*Sleep 5 seconds before closing.*/
   //sleep(5);

   return (0);
}


Running it, one gets

$ DISPLAY=127.0.0.1:0.0 ./getch_test.out
Press a key:
1
2
HANGS

it does not print "3", so it seems it does not return from

   XNextEvent(dis, &event);


I am not an X11 expert, so it could be I am doing the wrong things but 
the same code runs fine on OSX+XQuartz and GCC-4.9.1.

For completeness, I start the Cygwin X server with a link on status bar 
(W7+Cygwin64) whose target is:

   C:\cygwin64\bin\run.exe --quote bash -l -c "rm -rf /tmp/.X*; XWin 
-multiwindow -clipboard -silent-dup-error 2>/dev/null &"


Ciao,
   Angelo.

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Re: An issue with libX11?

[Jon TURNEY]

On 09/11/2014 15:38, Angelo Graziosi wrote:
> From another application I have an issue with libX11 which I can
> reproduce with the following STC,

I don't think this test case is well-formed.

> int main()
> {
>    dis = XOpenDisplay(NULL);
>    win = XCreateSimpleWindow(dis, RootWindow(dis, 0), 1, 1, 500, 500,
>                              0, BlackPixel (dis, 0), BlackPixel(dis, 0));
>
>    XMapWindow(dis, win);

A 'XSelectInput(dis, win, KeyPress)' is needed here to tell the X server 
that this client wishes to receive KeyPress event.s

> I am not an X11 expert, so it could be I am doing the wrong things but
> the same code runs fine on OSX+XQuartz and GCC-4.9.1.

I tried with XQuartz 2.7.8_beta1 and I couldn't reproduce that.

-- 
Jon TURNEY
Volunteer Cygwin/X X Server maintainer

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Re: An issue with libX11?

[Angelo Graziosi]

Il 09/11/2014 21:16, Jon TURNEY ha scritto:
> On 09/11/2014 15:38, Angelo Graziosi wrote:
>> From another application I have an issue with libX11 which I can
>> reproduce with the following STC,
>
> I don't think this test case is well-formed.
>
>> int main()
>> {
>>    dis = XOpenDisplay(NULL);
>>    win = XCreateSimpleWindow(dis, RootWindow(dis, 0), 1, 1, 500, 500,
>>                              0, BlackPixel (dis, 0), BlackPixel(dis, 0));
>>
>>    XMapWindow(dis, win);
>
> A 'XSelectInput(dis, win, KeyPress)' is needed here to tell the X server
> that this client wishes to receive KeyPress event.s

I found the issue trying the examples of libXbgi library 
(http://libxbgi.sourceforge.net), so I tried to create a STC adapting 
the example discusses here:

https://user.xmission.com/~georgeps/documentation/tutorials/Xlib_Beginner.html

Anyway, the STC on Cygwin64 doesn't work if I add your suggestion,

...
XMapWindow(dis, win);
XSelectInput(dis, win, KeyPress);
XFlush(dis);
...

>
>> I am not an X11 expert, so it could be I am doing the wrong things but
>> the same code runs fine on OSX+XQuartz and GCC-4.9.1.

as I wrote, on OSX it works (there XQuartz is 2.7.7). For this reason I 
flagged this to X-Cygwin list..

> I tried with XQuartz 2.7.8_beta1 and I couldn't reproduce that.
>

On which system? OSX?


Ciao,
  Angelo.

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Re: An issue with libX11?

[Jon TURNEY]

On 09/11/2014 20:49, Angelo Graziosi wrote:
> Il 09/11/2014 21:16, Jon TURNEY ha scritto:
>> On 09/11/2014 15:38, Angelo Graziosi wrote:
>>> From another application I have an issue with libX11 which I can
>>> reproduce with the following STC,
>>
>> I don't think this test case is well-formed.
>>
>>> int main()
>>> {
>>>    dis = XOpenDisplay(NULL);
>>>    win = XCreateSimpleWindow(dis, RootWindow(dis, 0), 1, 1, 500, 500,
>>>                              0, BlackPixel (dis, 0), BlackPixel(dis,
>>> 0));
>>>
>>>    XMapWindow(dis, win);
>>
>> A 'XSelectInput(dis, win, KeyPress)' is needed here to tell the X server
>> that this client wishes to receive KeyPress event.s
>
> I found the issue trying the examples of libXbgi library
> (http://libxbgi.sourceforge.net), so I tried to create a STC adapting
> the example discusses here:
>
> https://user.xmission.com/~georgeps/documentation/tutorials/Xlib_Beginner.html
>
>
> Anyway, the STC on Cygwin64 doesn't work if I add your suggestion,
>
> ...
> XMapWindow(dis, win);
> XSelectInput(dis, win, KeyPress);

Oops.  I think that should be KeyPressMask.

> XFlush(dis);
> ...
>
>>
>>> I am not an X11 expert, so it could be I am doing the wrong things but
>>> the same code runs fine on OSX+XQuartz and GCC-4.9.1.
>
> as I wrote, on OSX it works (there XQuartz is 2.7.7). For this reason I
> flagged this to X-Cygwin list..
>
>> I tried with XQuartz 2.7.8_beta1 and I couldn't reproduce that.
>
> On which system? OSX?

XQuartz doesn't run on anything else :D

-- 
Jon TURNEY
Volunteer Cygwin/X X Server maintainer

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Re: An issue with libX11?

[Angelo Graziosi]

Il 09/11/2014 22:16, Jon TURNEY ha scritto:
> On 09/11/2014 20:49, Angelo Graziosi wrote:
>>
>> ...
>> XMapWindow(dis, win);
>> XSelectInput(dis, win, KeyPress);
>
> Oops.  I think that should be KeyPressMask.

Now, it works as expected. Thanks..


   Angelo

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